A liquid crystal display device is an appliance for displaying images by using liquid crystal.
In order to display images, a conventional liquid crystal display device includes a light supplying part for generating light required for displaying images, an optical part for making brightness distribution of the light to be uniform, and a liquid crystal control part for controlling the liquid crystal.
For example, the light supplying part of the liquid crystal display device includes a cold cathode fluorescent lamp (CCFL) that generates white light and has a relatively low heat-producing rate with long life span.
The optical part uniformly distributes the brightness of the light generated from the CCFL. Although there is a small difference according to kinds of the liquid crystal display devices to be used, the optical part basically includes an optical sheet.
The optical sheet includes a diffusion sheet for uniformly distributing the brightness of the light generated from the CCFL by diffusing the light generated from the CCFL, and a prism sheet for collecting a light exiting from the diffusion sheet.
The optical part may have a light guiding plate. The light guiding plate changes the light generated from the CCFL into a light having an optical distribution of a surface light source.
The liquid crystal control part controls the liquid crystal in a pixel unit, such that transmissivity of light processed by the optical part can be controlled in a pixel unit. Thus, images are displayed by the liquid crystal control part.
Among the light supplying part, especially the optical part affects a great influence on display quality of the liquid crystal display device.
The above-mentioned diffusion sheet or prism sheet of the optical part is fixed by using a double-faced adhesive tape, or fixed to a boss by forming a hole at an extension part of the diffusion sheet or the prism sheet.
However, since the optical part is manufactured to have a thin sheet shape by using synthetic resin, the optical part easily expands by heat.
When the optical part expands in a state that the optical sheet is securely fixed by the double-faced adhesive tape, wrinkles are created on the optical part, so that display quality is deteriorated. In other words, the wrinkles created on the optical part cause stains to be shown when images are displayed.
In order to solve the above problem, there is an attempt to movably fix the optical part.
However, when the optical part is movably fixed, the optical part makes a friction with respect to the liquid crystal control part that is adjacent to the optical part due to external vibration applied to the optical part.
When friction occurs between the optical part and the liquid crystal control part, scratches are created on the liquid crystal control part or the optical part, thereby deteriorating display quality.